camphor-10-sulfonic acid in benzene Heating;

1: p-TsOH / CH2Cl2 / Ambient temperature 2: LiAlH4 / diethyl ether / 0.33 h / 0 °C View Scheme

Stage #1: With  1-hydroxy-pyrrolidine-2,5-dione; dicyclohexyl-carbodiimide in  dichloromethane T=20°C; 12 h;  Inert atmosphere; Stage #2: With  sodium tetrahydroborate in  tetrahydrofuran; ethanol T=0°C;